View Full Version : Tile replacing vinyl floor on concrete

01-14-2007, 09:07 PM
I've asked questions about this project on John Bridge's forum but would like some input from you guys. Here's a little bit of the floor I'm concerned about.
This is about a 3' x 5' area of 20+ year old vinyl glued very firmly on concrete and appears to possibly be on top of SLC or a fairly thick layer of something. I would like to totally avoid having to get that vinyl up and am thinking seriously about putting something over it. Problem is that the tile will extend thru a door into a 4 x 8 area which at this time is a carpeted concrete floor in a powder room area. These floors need to be on the same level and there are no cracks to be concerned with. I am not at all convinced that this is a job that would require ditra. Hardibacker has been suggested. I just would like to know (1) How would YOU bring the floors to the same level. (2)How would you attach any underlayment you might suggest. (3) what kind of mortar that is sold at the big box stores would you choose?

01-15-2007, 11:27 AM

I have no interest in going over to the JBF site; I might go back later when I feel up to it.

- Question 1.) We have almost enough information to be able to answer it.
- Question 2.) Easy. Use a glue or cement, depending on what the maker of the underlayment suggests. :)
- What is Question 3. about? Thinset mortar for tiling? A possible mortar to bring the floor areas to the same level?

About adding a CBU on top of concrete: NO. There is risk, and there is no advantage and no gain (except the "gain in height"). If you want to thicken your floor, gaining that much height, with a hard cement product, just use a dry bagged cement product that you mix with water and spread out with a trowel. It costs less than CBU too. Call a cement manufacturer and they'll tell you about patching mix, resurfacing mix and grout mix. (So, AFAIK, CBU is for wood substrates.) Call Hardie or view the web site to see if they warrant tiling on CBU on concrete.

You have two distinct floor areas and a door between them -- is this right? Are you planning a door sill? If you could put that in the plans, it will give you a few big advantages. For one, you now can do what is right for each floor area, and let the sill plate (e.g. marble) handle the break. Each floor area gets a tile layout that is right for it. Your one area gets the underpadding or filler treatment that it needs. If you ignore all this, I believe you can still tile over the break in the two types of underlayment and not risk a crack, but that depends...

In 2005-2006 I spent time at that other site. No-one ever gave a straight answer about tiling on a concrete surface. More than one key player talks about adding "mud" on top of concrete slabs if no D*tra. In other words, no-one says "no" to alternatives but no-one confirms. It appears as Either you add "2 inches of mud" or you put D*tra down.

Truth is, you can tile directly on top of a concrete slab or on top of any underlayment made for tile that you peel-and-stick, glue, or thinset, onto the concrete. At that site, all the non-orange membranes (or underlayments) get short shrift since they give more options to the newbie DIY who may then not buy the big orange membrane in the sky. That's in their DIY forum. In the Pro forum inside JBF there is a lot more truthful discussion of the issues, but Pro's are gently warned not to "confuse" the general public DIY. This keeps the Pro's under control, segregated and partially muzzled (in return for freebies). But even in the Pro forum, there is a lot of voluntary self-censorship. Cork has been used as a tiled floor membrane for centuries, and they make it seem risky, never-heard-of-in-these-parts, likely to fail and likely to rot. Other synthetic products get ignored; some get "confused". Orange membranes are worth a lot of money to them.

In your application, if you want to buy a synthetic membrane, I could name a dozen that will all work. You're on concrete after all, and that is the best starting point for a tile floor!


01-15-2007, 12:52 PM
Thanks David. I felt that the answers I was getting over there were more like trying to get me to buy something I don't need. Seems that one was trying to persuade me into thinking that the concrete was going to crack (it hasn't in over 20 years!) and that I had to have a membrane to prevent this from destroying a tile job. If I could get the tile up and clean the glue off of the concrete with little trouble I'd go directly over the concrete with the tile without question. Time is the big factor why I don't want to pull up the vinyl. This job is 125 miles away and the travel and motel bills can eat up any profits quick if I don't do a very good and very efficient job. I'd rather spend an extra $100 on materials than spend an extra day preparing the surface of a 3 x 5 area or 4 x 8 area.

Question 1: The vinyl appears to have something like SLC under it ...so, the vinyl and whatever is under it is about 1/4" above the concrete. The carpet padding is directly on concrete. There will be NO transition between the rooms...so, I've either got to take one floor (vinyl) down or bring one floor up (the carpeted area).
Question 2: Hardibaker was suggested and screwing it down was how that guy would attach it... as if on wood.
Question 3: There are several different mortars to attach tile to whatever underlayment is used. If I use a membrane I want to use whatever is best to hold the membrane (or CBU) to the concrete...and I want the correct mortar to hold the tile to whatever is under it. Ultraflex 2 was suggested if I go with the 1/4" hardibacker.

I'm wondering how it would do if I just pour SLC over the whole thing then just act like it's all concrete and use a good mortar to set the tile in.

01-15-2007, 02:31 PM

leaving whatever it is, vinyl or linoleum or laminate or whatever, is risker than removing it and starting from zero. But it takes a lot of time. So discuss this with your client. All thinset manufacturers say their thinset will work over solidly attached vinyl or lino. Read the label, call their number, deal with them about the finer points.

Raising the cement level above a slab is not a big deal. I would never use SLC unless I felt sure about it. It is a finicky product and has caused a lot of people to waste time chipping it out and starting all over again; sometimes it doesn't even level itself out, and you have to trowel it and babysit it just like real cement. If it were me, in this space, I would use a real standard boring cement product, after calling the cement manufacturer whose products are available in my area and telling them what i have to work with. I would only prefer SLC if the floor area were badly in need of being made flat and level like if it had low spots, bumps and were totally not level from one wall to the opposing wall. This isn't what you have here, as your floor is already flat and level. Unless you missed telling us that. So, no, no to SLC. It is not rocket science to use a trowel and a level to put a 3/8" layer of new cement in a 4'x8' space; there is no call for SLC here.

What you might like to spend money on is a product that hardens within a couple hours instead of overnight.

The big big thing overlooked so far is the control joint. The two rooms are like two plates, and between these two plates is a break in the under-layer, and a break in the "geometry". They meet at a door and that is also where the underlayment is DIScontinuous, so you do risk a crack through tiles there, at the door sill, within a couple years. The same firm that makes D*tra also makes metal-rubber-metal control joints. You'll find them on their web site. At the very least you have to plan for this stress crack, unless your client waives that responsibility. Other methods of controlling the millimeter slippage under tiles that can cause a crack include a patch of thin membrane, on top of your floor under the tiles, made by Noble. It's like a 1/16" neoprene pad.

all of the above assumes you want a flat level surface to tile on so that you only have to deal with a single size of groove in your thinset trowel.

p.s. if you feel that a control joint is overkill, at least plan for a grout joint there, that you can fill with epoxy grout not cement grout, since epoxy can flex a bit.

01-15-2007, 05:40 PM
You say the powder room is only 4 x 8, right? So tile the whole darn thing. That will give you the level surface the customer wants, and then re-carpet right over the newly laid tile. We're only talking about 32 sq ft in the powder room. $50 bucks max.......probably less.

01-16-2007, 07:29 AM
pewter... I'm ripping out the carpet to put down tile. The floors are uneven because the toilet & tub area are covered with vinyl... when the carpet comes out there will be bare concrete in that area and then I'll have to deal with the vinyl in the other. Definitely the quickest way would be to throw down some mortar to bring the bare concrete up the to level of the vinyl then cover the whole thing with hardibacker and tile. I just don't know if that would leave a danger of the hardibacker bucking. I've got a half a mind to just tape it and use ultraflex 2 to hold the tile to the hardiboard to make it a floating floor so that expansion won't be a problem...but then I'd worry a bit about it flexing if I didn't use some kind of mortar under the hardibacker. I'm not in favor of screwing it down to the concrete. I'm totally ignorant about the use of membranes other than in showers.

01-16-2007, 03:39 PM
Gotcha........ I thought she wanted carpet in the powder room, and tile in the bathroom.
I'm no pro, but here in Fla, tile goes right down onto the slab with the just thinset. The only prep would be to caulk any cracks. It's my impression that a concrete slab is the perfect start to a tiled floor.
How thick is this lino in that bathroom? The best thing would be to get it off the floor, but I understand why you would rather not. If the transition is not too, too bad, then what about using a different size trowel? Use the smallest possible notched trowel in the bathroom, and then use the largest possible trowel in the powder room. That would give you a thicker mortar bed, at the very least. Even if you were to do this at the transition area only, I think you could make it work cuz it's such a small area. If we were talking about transitioning from the kitchen into the living room, then I'd say no, cuz it would stick out like a sore thumb.
Of course the whole thing hinges upon whether that lino has to come up or not.

01-16-2007, 06:14 PM
The HardiBacker must be anchored to the floor - you must use either screws or nails, neither of which will workwithout major pain into a concrete slab. When you put down a CBU, the mortar under it is not actually holding it in place - it is filling any minor imperfections or voids so the tile is fully supported.

A razor scraper and maybe a heat gun might take the vinal off quicker than you think. Whatever is under it that is not part of the slab may or may not come off easily. SLC is fairly expensive, has its quirks, but does work if you do all of the prep work and follow the instructions to the letter. If the vinal is NOT cushioned and well adhered to the subsurface, AND you use the proper thinset, it should work. That won't get you level with the area carpeted, though.

My personal experience at johnbridge.com is that they lay out the options - the TCA handbook lists often 3-4 ways that will work in any given situation. Presenting them all can seem like indecision, but it is not. The use of membranes can help in certain situations and often offer some significant labor savings. Cutting a membrane to size and preparing a room for tile is MUCH quicker with stuff like Ditra or other brands of membranes and is much eaiser to carry home! So, don't discount the advice.

01-16-2007, 06:34 PM
The whole deal I have with the vinyl is the difficulty of getting it up and whatever is under it. If I could be certain that there would not be alot of adhesive or leveler under it then I'd rip it up and throw down the tile...no question about it. Not knowing what is under the vinyl or if I can in fact get it up I'm leaning toward just covering it up then laying the tile on top. I suppose my biggest problem with using a membrane is I'm just ignorant about that and still do not understand how it would benefit the situation OR how it is adhered to the sub. If the membrane does what I understand it does then it seems reasonable to assume that I could just bring up the rest of the area to the level of the vinyl, lay down the membrane, then lay down the tile...still, what kind of thinset/mortar/glue goes under and over the membrane? It's just that before I get 125 miles from home and invest two days on this job I absolutely must be prepared and know ALL the alternatives... ain't no half stepping.

01-16-2007, 07:21 PM

i really think you cannot use the Hardi over a slab. Besides, why put cement upon cement?


01-16-2007, 07:40 PM
Hardi will not warrant their cbu over a slab and if time is a factor as you say, the only thing you could do to try to mitigate the attachment required would be to drill hundreds of holes in that old, hard concrete slab and use something like Tapcons to anchor it properly - it is designed (along with all of the other cbu's out there) to provide a decoupling layer between wood which moves, and the tile which doesn't.

If you could be assured that there actually was a layer of something under the vinal, a small demolition hammer would probably chip the layer off fairly quickly.

WIthout being there, it is hard to tell. If you are worried about the job, maybe you should pass it on to someone closer.

01-17-2007, 04:26 AM

no to CBU on a slab. Crunch crunch, that is the noise it'll make all the time. You can hear it through the tiles.

get fast-setting cement and build up the floor. Some products harden in 90 minutes. Or, buy a tile underlayment (pad) almost thick enough to build up the floor sufficiently. E.g 6mm cork sheet, designed to go under tiles. Then with the right-size trowel you get the exact height you want by making your thinset just the right thickness.


Besides, you now have the most serious technical reason why not, "it is designed to be a decoupling layer between wood which moves..." because of humidity changes, and tiles which move because of temperature changes.